Nginx如何根据url中的path动态转发到upstream

location ~* /(srv[1-9]+)/(.*)$ {
  allow all;
  proxy_pass http://$1/$2$is_args$args; 
  proxy_set_header host $host;                         
  proxy_set_header x-forwarded-for $forwarded_addr;                                
}

upstream srv1 {                                                   
   server srv1-ip:8080;
}
      
upstream srv2 {                                                   
   server srv2-ip:8080;
}

location ~* /(svc[1-9]+)/(.*)$ {                             
  allow all;                                  
  proxy_pass http://$1/$1/$2$is_args$args;                   
  proxy_set_header host $host;
  proxy_set_header x-forwarded-for $forwarded_addr;                   
}

upstream svc1 {
  server srv1:8080;   
  server srv2:8080;   
  server srv3:8080;                
}

upstream svc2 {
  server srv3:8080;   
  server srv4:8080;   
  server srv5:8080;                
}